


Under the Sea

by CaptainThirsty1945



Category: Captain America (Movies), Captain America - All Media Types, The Avengers (Marvel Movies), The Avengers (Marvel) - All Media Types
Genre: Alpha Bucky Barnes, Alpha/Beta/Omega Dynamics, Alpha/Omega, Alternate Universe, Alternate Universe - Canon Divergence, Alternate Universe - Fantasy, M/M, Merman Bucky, Mpreg, Omega Steve Rogers, Pre-Serum Steve Rogers, merman steve
Language: English
Status: In-Progress
Published: 2016-03-12
Updated: 2016-06-20
Packaged: 2018-05-26 05:30:25
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 9,373
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6225847
Author URL: https://archiveofourown.org/users/CaptainThirsty1945/pseuds/CaptainThirsty1945
Summary: <blockquote class="userstuff">
              <p>The sea is full of wonders, not all of them for the eyes of humans. Steve and Bucky happen to be one of them. When they get taken by marine biologists, it's clear pretty early on that these creatures aren't afraid to do whatever it is they feel is right. </p><p>Or the one where both Steve and Bucky are merman and just really wanna go home.</p>
            </blockquote>





	1. From Bad to Worse

With all of the hundreds of thousands species of marine life living in the ocean, it’s never really a surprise when a new one shows up, or when legends are born from the mysterious depths. There’s a common legend told about people with fins instead of legs living in the ocean in the city of Atlantis. This tale has been told countless times, but none of them have ever really been the complete truth. Some of these tales make them out to be curious or gentle creatures who might fall in love with humans. However, that is not the case. Most of these mythical creatures are dangerous, with their siren songs luring sailors into their icy cold embrace. In the ocean, there are pods of this fish-like people, traveling all throughout the different oceans, migrating with the various seasons. If a human is unlucky enough to spot one of two possible fates await. An instant death given by an Alpha ripping out the poor human’s heart, or a slow death given by the Omega whom will sing and then drown their victims. No one has ever lived to see one of these creatures and been able to tell about the experience. But clearly, it was time for the story to change.

Bucky was having a wonderful nap under the wave in a cove not yet explored by the ever curious man, spread like a cat does in the sunlight on his smooth rock. He only looked up when he heard his little Omega come back from his trip to the reef, not at all quiet as he swam. “Buck! I got you a present!” he chirped, only making Bucky wish that his Omega would just stay home and weave seaweed like he wanted. Not that he would  _ ever _ tell Steve that, given that the little blond in his five foot, skinny as a toothpick had fury big enough for a killer whale. It was all too easy to forget that Steve was stronger than he looked. “It’s really pretty,” he stated as he swam closer, sitting himself on the rock next to his Alpha. “I found it over by the beach,” Steve stated as he reached for Bucky’s arm.

“You didn’t get spotted did you?” Bucky asked, squinting at Steve somewhat suspiciously. The last thing they needed were humans snooping where they didn’t belong. Granted, he knew that if any humans were to see them, they could probably just kill them off, but he honestly wasn’t in the mood to kill anything that he didn’t feel like eating today.

Bucky was rewarded with an amused eyeroll. “No, I didn’t get caught. I got you a nice bracelet though. Give me your arm,” he hummed, clearly all pleased with himself as Bucky did as he was asked. He offered Steve his arm as he watched the Omega put a slim silver bracelet with a little ruby red star charm dangling off of it. “It was half buried in the sand. I rescued it,” he stated before he leaned over to nuzzle Bucky’s face affectionately. “Way better than anything I could have weaved, don’t lie to me, Buck. You like the shiny things just as much as I do. Maybe even more…” he teased before he stole a kiss, Bucky happily leaning into him.

“Mmmm, you know me so well,” the brunet chuckled softly when he pulled away. He wrapped his arms around Steve’s waist, smiling up at him as he pulled Steve down for another kiss. “I do however, think it’s time to go hunting. Can’t let my Omega starve after all. What do you think?” he teased before Steve nodded, all smiles as he flashed his sharp teeth. 

“Mmmm, fish does sound pretty good right about now… I wanna cuddle though…” he pouted, nuzzling into the bond mark on the juncture of Bucky’s neck and shoulder as the Alpha suppressed a moan. 

“Come on, Stevie. I won’t be gone long. We can cuddle right after I catch us something to eat,” Bucky offered, tightening his grip a little bit around Steve’s waist. He kept trying to fatten his Omega up, but no matter how hard he tried, he never seemed to get any meat on his bones. It was like he was a skeleton with skin that could swim around and provide warmth.

“...Alright. That sounds like a good plan. Do you care if I go out exploring some more? I wanna see if I can maybe find a necklace to match the bracelet I gave you,” he hummed, pushing himself off of Bucky’s chest a little so he could get a better look at him. “Please? I promise to stay out of trouble.”

Bucky sighed, nodding his head. “Fine. Just don’t get seen by anything, okay? I don’t like worrying about you. And if you do get seen, yell for me, okay? So I can help you kill them. Not that I think you need the help but… Just in case there’s more than one,” he pleaded softly, kissing his Omega’s chin.

“I guess I can do that…” he pouted. Steve didn’t understand why Bucky worried so much. He could take care of himself after all… I mean he’s made it this far right? Sure, he’s never had to kill anybody but that’s neither here nor there. He could if he really wanted to… Or so he’d like to think. “I won’t go far. Try not to be gone too long, okay?” he hummed as he gave Bucky another kiss before his Alpha nodded as he went go to grab his spear. 

“I’ll be back before you know it, Stevie,” he hummed as he began to swim away to catch them something to eat. “Yell if you need anything!” he yelled over his shoulder before he was gone from sight. Steve immediately swam back to the cove where he’d found the bracelet, only noticing the boat when he’d gotten closer. He’d never been this close to humans before, curiously swimming closer.

“Hey, we just got a call from a fishing boat that something in the water is stealing some of their fish,” a balding man wearing strange shiny clothes said to a brunet man with a goatee. Steve frowned, swimming slightly closer under the waves.

“Do they know what it is? Did they offer a description?” a different brown haired man with strange clear shiny things over his eyes asked, frowning at the other two. It looked like there were four of the humans on the boat, the balding man, the brunet with the goatee, the brunet with the strange shiny things, and a big burly looking guy with brown hair and a nasty look on his face.  

“No description was giv- wait. What’s that?” the balding man stated, making Steve panic,  as he quickly swam deeper under the surface. “It looks big, had a shimmery blue tail. Someone get me a fish, I’m gonna go investigate,” the man with the goatee stated before he held a fish over the edge of the boat. The human only flinched back when a human-like hand shot out of the water to steal the fish in his hand. Steve swam back deep into the water after he’d stolen the fish, eating it pretty quickly before he curiously swam back up. The goatee man offered him a new fish, Steve quickly grabbing it before something wrapped itself around his tail. He immediately started panicking, thrashing around in the water. The burly man hauled Steve on the boat, only making the Omega lash out and scream more. With Steve’s high pitched screaming came Bucky’s worried responding calls, clearly responding to the sound of his distressed mate.

“Shit- Sounds like there’s a bigger one heading our way, probably dangerous. We gotta go,” the man with the goatee stated, helping the burly man get Steve further onto the boat so he could untie the rope from around his tail before the poor creature hurt himself. Not that he seemed very willing for any help at all from them.

“Get me a sedative, we have to shut this one up first. He’s only spurring him on, calling him this way. It won’t help us if he sounds as agitated as he does,” the burly man stated with a sarcastic eyeroll, clearly disinterested with what was going on between the creatures and the boat that just happened to be here at the wrong time. The balding man quickly gave a sharp pointy object in a tubey thing to the burly man before quickly injecting it into the panicked merman. Steve’s high pitched and distressed calls for his mate quickly dying as he was knocked out by the drugs. This of course, only made Bucky more worried as he rammed himself into the side of the boat, calling for his mate. When Steve didn’t respond, he rammed himself into the boat again, more distressed than ever before as he tried to tip the boat over. That however, is when the boat roared to life, startling Bucky enough to freeze him up before he let out a shriek of pain due to the propellers shearing off his left arm. The boat was gone in what felt like a blink of an eye as it sped away with his Omega. Bucky kept up with it as best he could in his condition, the ocean water not really helping to keep him from bleeding out all over the ocean.

The humans who had Steve however, seemed to be having a field day with all of the scientific evidence that now had suddenly landed in their laps. “We need to keep him sedated until we get back to the aquarium, okay? I don’t need him waking up on the plane ride home and scaring everyone onboard. We also need to keep this on the down low until we know exactly it is we’re dealing with. Call someone else in to get the other one, tell them that they’ll probably need a med kit and probably a sedative to keep him from biting anyone’s hands or faces off. Got it? Good.” the man with the goatee stated as he started checking Steve over for anything that could be useful in identifying him.

“You think they were in a pod together, Tony? Maybe that’s why the other one seemed so keen to get this one back?” the balding man asked the man with the goatee. 

“I dunno Phil, we can’t really find out until we investigate the two we have. We need to see how they work. They appear to be social creatures. Dependent on meat if their sharp teeth and claws are anything to go by. I’ll write up an official lab report when I get back to my lab,” he sighed, scratching at his goatee as he got a towel wet to spread over Steve’s tail. 

“Don’t worry, Phil, I’ll make sure he doesn’t forget,” the man with the shiny things over his eyes stated, smiling at him sheepishly.

Phil nodded, sighing deeply as he rubbed his face. Honestly, they were only planning on checking out the coral and they come away with a whole new species? One that seems extremely developed if you asked his professional opinion. “Let me know as soon as it’s done okay? I’d like to have something for Fury to look at as soon as possible. Maybe see about getting whatever this is, accustomed to a tank for display, preferably before the month is out. We all know that this will bring the people we need to keep Pierce from pulling the plug on us,” he sighed, making the other two men sigh in agreement. Getting laid off was the last thing they needed, especially with all of the animals they had to care for in the picture. Including this new creature, one that they had only ever heard about in legends and fairytales.

When Steve woke up after the effects of the drugs wore off, he was in the smallest single body of water he’d ever seen in his life. His memory was kind of foggy, and he didn’t recall getting off of the boat that had taken him, nor how long he’d been out. Bucky was nowhere in sight. He tried calling out for his mate, but got no responding call back. He didn’t realize that he’d already been looked at by the humans that had taken him from his home, from his mate, nor did he realize that it was going to be a long time until he ever saw the ocean in anything other than pictures. He did however, realize that he needed to get out of there, as soon as possible.

* * *

Official Lab Report on Specimen M1945, Written by Stark, Anthony Peer Reviewed by Banner, Bruce (20XX) for Director Fury, Nicholas J. of SHIELD Aquarium

The creature we found off the coast of Hawaii seemed to be identical with the legends of merfolk, or other such creatures of the sea. He has the upper half of a human,and the lower half of what appears to be shark. He has blond hair, pale skin, and blue eyes that match the scales on his lower half. He’s most definitely male. The specimen is approximately five feet and four inches tale from the top of his head all the way to the end of his tail and weighs approximately 176 pounds. The sharp teeth and claws lead me to believe that he eats other fish. This was only proven when he ate the offered fish we offered him before the initial capture. 

His tail is slightly bruised from the rope that Rumlow, Brock had wrapped around it, but seems to be easily hidden under the scales. Speaking of his scales, they feel kind of like how a shark’s are, almost like skin, but still similar to sandpaper.

Currently it’s unclear how they interact in the wild, but they appear to be social creatures considering that as soon as the specimen started yelling, a new one emerged to defend him. I’m not sure how the mating works yet within this species, but we’re hoping that we can teach the specimen we have some form of communication to ask it direct questions. Maybe he can shed some light on his species and how we’re never seen them before now.

 


	2. This is Getting Out of 'Hand'

**Summary for the Chapter:**

> Honestly, this is all starting to get out of hand.

The merfolk say that when a bond is strong enough, the two mates can feel each other’s pain. It’s also said however, that distance is something that should forever be avoided when it comes to feeling each other through the bond, because as the distance grows, the pain lessens. Initially, Steve should have felt Bucky losing his arm, but instead, all he’d felt was an empty cloud of nothingness. When he’d finally woken up and was actually coherent, he hadn’t felt much besides a gentle ache in his arm like he’d slept on it wrong. For Bucky though, that pain had been intense. When he was awake to actually feel it, he was swimming in the direction he’d seen the boat go. He hadn’t gotten the bleeding to stop, but it had gradually slowed down as he kept swimming, looking for any sign at all that his mate was okay, or where he’d been taken. Bucky swam for a grand total of thirty-seven hours before the same people who’d taken Steve came back for him. The poor Alpha was near death considering how much blood he’d lost, and was delirious as he tried to take the burly guy’s hand off. For obvious reasons, he didn’t trust the humans who’d taken his mate, who were taking him. He wanted nothing to do with any of them. It wasn’t until he was sedated that he even remotely calmed down, but he was bigger than Steve, meaning the dose they’d given him was only enough to calm him down a little bit, not completely knock him out.

“Tony, this is Coulson. I found the bigger one. He needs immediate medical attention or we’re going to lose him. Get down here as soon as you can,” the balding man stated into a strange box-like contraption.

“Affirmative. I have the one we got yesterday partially sedated in his tank. I was afraid he was going to hurt himself. I’ll be there as soon as I can. Heading your way now. I’ll call Bruce and let him know to get the lab ready. And to get one of our trainers over by the new arrivals tank,” the box crackled back, making the balding man nod as he looked over to Bucky. The Alpha weakly glared at him back as he growled tiredly. The man he was guessing was named Coulson fiddled with his box before it crackled back to life.

“This is Coulson, who is the trainer on duty at this time?” Coulson asked his strange talking box, only having to wait a few moments before it crackled back to life.

“Hey Phil, this is Sam. Natasha is working with Clint in the orca tank right now,” a new voice replied.

“Wilson, hello. I need you to go to our new arrival and make sure he has everything he needs to be moved to a different tank. I’ll talk to Fury about putting you in charge of him, if you think you can handle it,” Coulson stated as Bucky stared at him. The Alpha really hoped they were talking about Steve. All he wanted was to make sure his Omega was okay, and possibly hit him over the head for being such an idiot. He’d told Steve to stay away from boats and to yell if he saw any humans. But here he was, getting taken by them, put in tanks… He didn’t even know what a tank was but it sounded terrible. He’d probably have to stay away from those if he wanted to get home soon, with his Omega preferably. God, he never thought he’d miss his cave, but here he was…  “We have his… Friend coming in. We’re going to keep them separate until we know that this one is going to be okay. The last thing we need is them accidentally killing each other,” Coulson stated as Bucky growled at him again. If he heard them right, this guy wanted to keep him _away_ from his Omega. Keeping them apart was probably the worst thing they could be doing, go figure.

Bucky yelled out in outrage, his high pitched clicking only making the humans currently on the boat flinch away from him. Honestly, Bucky hoped they all suffered terrible fates for keeping him away from the Omega who honestly did the stupidest things in spite of himself. What was he supposed to do with himself if he was forced to be alone? Close and yet so far? He already knew he’d go crazy, he was predicting his fate now, while he was still sane. The burly man he’d tried to bite before came back over so Bucky decided he’d try to claw his face off this time. He snarled back at Bucky, clearly finding this display of dominance a waste of his oh so precious time.

“Brock, stop instigating and sedate him. He’s not going anywhere, but the more he struggles, the more blood he’s going to lose,” Coulson snapped, glaring at the human Bucky could only assume was Brock. God, all these humans had terrible names. He almost felt bad for them, given their lack of fins and clear lack of good taste. He was almost curious underneath all of his pent up anger at losing his Omega. Steve honestly couldn’t live on his own, not with how reckless he acted. Bucky needed to be there for him, keep him safe, make sure he didn’t do anything _else_ stupid. Pretty much everyone they knew, knew that Steve needed to be watched, for his own protection really. Like the time he’d tried to wrestle a shark to prove to everyone that he wasn’t what his body said he was. He’d almost gotten eaten that day. If Bucky hadn’t been there, he had no doubt his Omega wouldn’t even be around to have been captured.

Bucky’s attention snapped back to the present when Brock came back over with a long pointy looking… Whatever that thing was. Coulson took the pointy thing from him as Brock held Bucky’s arm down. The Alpha, for obvious reasons, fought back, thrashing around as he tried to pry him loose, get a good angle to bite off maybe a finger or two. The noises he made were loud and high-pitched as he clicked and bucked his tail around. Before he even knew what had happened, the sharp pointy thing had already been inserted into his arm. His movements became sluggish as he tried to process what had happened. With his last bit of conscious thought, he glared daggers at the two humans who had drugged him and taken him and his mate away from their home. If looks could kill, he was sure that both of them would have been simultaneously fallen off the both to have drowned to their deaths, forever lost at sea.

By the time Coulson and Brock had made it back to the aquarium, Bucky had been out cold for a few hours. They hefted him into a small tank before quickly wheeling him to Tony and Bruce’s lab. “He’s lost a lot of blood. That doesn’t seem to stop him however, from being aggressive. So it’s probably for the best to keep him sedated until you patch him up,” Coulson stated after they’d situated Bucky a little better so Bruce could work on patching up his arm. “I’m going to go check with Fury to see if we can hopefully make their tank a little more welcoming. It might make the transition from the wild a little more bearable for them,” Coulson stated as he headed out the door, Tony following after him.

“Hey so, I called up Sam to see if should he could come down and hopefully teach the smaller one some English since he seems to be less aggressive than the one you guys brought in. Maybe have him teach him the basics since he’s training the small one anyway.” Tony paused for a moment, scratching his goatee. “Sam is their trainer right? Sam for the smaller one and Natasha for the bigger one? Hopefully Wilson can get them to spill their names. Because I’m almost positive they already have them. Hopefully nothing too hard to pronounce. But you know, we could always name them,” he stated, nodding to Coulson. “Anyway, you go talk to eyepatch, I’ll be here. Taking measurements and recording data. Because honestly I’d love to go down in history for this. Not that I’m _not_ famous, but good publicity like this never hurts.”

“Bye, Stark. Keep me posted on how they’re doing. I’d like to be able to give Fury a good word so we actually have something decent to tell the press,” Coulson sighed, shaking his head at Tony. Honestly, he was pretty predictable. Everything was either about something new that he invented, or about how he could get better PR because his current inventions were great, thank you very much. He sighed again as Tony mock saluted, watching as their number one donor went back to work on whatever it was he actually did. Honestly Coulson wasn’t even sure what that was given that Stark had so many PhDs. As Coulson went to go talk to Fury, Steve was busy hiding out in his tank. The Omega had swam the length of the tank what felt like seven thousand times, and it was pretty clear he was getting antsy. No one had approached him since he’d woken up, meaning he hadn’t heard anything about Bucky either. He missed him.

He was only pulled out of his thoughts when a fish hit the water, drawing all of Steve’s attention. Steve wasn’t hungry, but swam up to the surface anyway to get a better view on who was throwing fish into his small enclosure. On a small platform was a human with brown skin, a box of things next to him. It was the outfit that mostly caught Steve’s attention as he glared at him from the water though. He was wearing the same kind of outfit that the guy who’d given him the fish when he was taken. Steve instantly didn’t trust this guy, even if he looked friendly enough. “Hey, my name is Sam, I’m going to be your trainer,” he smiled, making Steve sink lower so that the water line was just under his eyes. “Can you come over here? I want to show you something. I promise you’ll like it,” he stated, clearly trying very hard for Steve to trust him. When the Omega didn’t answer, Sam sighed, leaning over so he could dig in his box, pulling out some flat shiny thing. “I have a picture of your friend. He’s sleeping here, but it’s him,” he stated, offering the object. Steve swam a little closer until he recognized his mate, immediately letting out a happy sounding series of noises as he quickly took the picture. He stared at it happily for a few moments before hugging it to his chest. It didn’t exactly feel the best against his skin, but he really didn’t care. He’d recognize Bucky anywhere. The Omega swam back up to the surface when Sam pulled a shiny box thing out of his box. “Here, we’re gonna go through the alphabet. I was told we need to get you speaking a little bit so we know what to call you and your friend,” he stated. Steve’s responding high-pitched clicks made Sam wince. “Yeah see, if that was your name, there’s no way me, or any of the other people here, are ever going to be able to pronounce that. Now, repeat after me,” he stated, holding a card that had an A on it. “A.” Sam said simply. Steve stared at him blankly for a moment before a look of concentration overcame his features. He slowly repeated it back to Sam, a smile growing on the human’s face. “That was good!” He chirped as they slowly made their way through the whole alphabet. Every time Steve correctly repeated something back to Sam, he’d throw him a fish.

Steve was elated when he got something right, gleefully chirping as he clapped his hands. It was clear that Sam was growing on him as he did a few tricks in the water, occasionally swimming back to the bottom of the pool to give his love to the picture Sam had given him of Bucky. By the time they were done, Sam had only one fish left in his bucket. “Okay. What’s your name?” Sam asked, holding the fish out.

Steve stared at him with a look of concentration on his face. “S...St… Stee… Steve?” The Omega didn’t sound sure of himself but that answer was better than no answer at all. Sam threw him the fish.

“I’ll see you tomorrow, Steve. With more fish. Your friend should be with you tomorrow if all goes well. Do you know how to pronounce his name?” He asked. Again, a look of concentration overcame Steve’s face as he tried to remember how to voice what he was thinking.

“B… Buck… Bucky…” he answered hesitantly before diving back into the water. Seemed a good a name as any.

“Alright, so the small arrivals name is Steve. His friends name is Bucky. Just figured I’d notify you so you can update their paperwork,” Sam stated over his walky talky. There was a stiff moment of silence before it crackled back to life.

“Good work. I’m finishing up here with the bigger one, and then we’re going to put him in his new tank. Bucky you said his name was?” Tony responded, an amused tone in his voice. “What an odd name. Granted this whole thing is odd. They’re basically the stuff of legends. I’m just surprised we haven’t found them before now.”

“Yeah, that’s fascinating. I’m going home. Bye Stark.” Sam sighed, turning off his walky talky as he made his way out of the park. Honestly, it felt almost like he was a kid going home from Sea World…

Tony was just finishing taking Bucky’s measurements when Bruce finished up his arm. “How’s it lookin’?” Stark asked, trying to get a peek.

“It looks like we really did a number on him. But he’ll be fine. I feel bad though… If he does get back into the wild, he’s going to be without an arm. He’d be like us with one arm. Which would make him less of an effective hunter,” Bruce frowned, pushing his glasses up a little higher on his face. The man next to him nodded, frowning somewhat as he put down his clipboard.

“I know. You think I should build him a new arm? It won’t be as good as the one he lost obviously, but it could hopefully help with things? Maybe make it look like the one he lost?” Tony mused as he scratched his chin. “Could be fun to build,” he stated before apparently coming to the conclusion that he was just going to build this creature a new one. It was their fault he lost it in the first place after all… “It’s settled. I’ll build him a new arm.” He hummed as he smiled over at Bruce. Bruce, his scientific husband, nodded as he helped move the heavy creature back into a portable tank. They wheeled him out to the tank that was connected to Steve’s, slowly letting him into the water.

Bucky woke up slowly the next day, calling out without really thinking about it, his tone lost and confused. The responding call wasn’t though. “Bucky!” Came a familiar voice that Bucky couldn’t quite place. “Buck!” The same voice called again. One of the humans from before was staring at him as if he expected him to do something back. Bucky only growled at him, swimming further underwater to hide from him. “Buck?” The voice sounded more hesitant this time, almost hurt sounding.

“Steve?” He called back gently, just to make sure and the response was instantaneous.

“Bucky! Where are you? I can’t see you- I’m sorry- I love you-” His Omega rambled, Bucky only catching some of what he was saying before a human he didn’t recognized told Steve something. The Alpha in him was outraged that they thought they could speak to his mate. It sprung Bucky into action as he swam closer at lightning speed, only stopping when he saw a glimpse of blonde hair. A gate thing moved out of the way before he saw his Omega, screeching in delight as he quickly swam to him, engulfing his arm around him as he clutched onto him tightly, Steve only giggled happily in response, holding him just as tightly. “Buck… I love you,” he stated quietly, pulling him into a kiss as he purposefully pulled him deeper into the water.

There was hushed talking above the water that the two mermen paid no attention to, instead choosing to snuggle on the tank floor. “They’re cute. But I don’t think they’re friends. They seem _way_ too familiar to be just friends,” Natasha stated, looking over at Sam. “The first of their kind, and they’re a homosexual pair. I feel that’s pretty fitting given today’s society, don’t you think?” He could only nod in agreement.

* * *

Official Lab Report on Specimen M1946, Written by Stark, Anthony Peer Reviewed by Banner, Bruce (20XX) for Director Fury, Nicholas J. of SHIELD Aquarium

The second specimen, dubbed as “Bucky” is much larger than the first of his kind, subject M1945. They both share the fact that they’re both male, the pointed teeth, sharpened nails, and odd ears that almost look like fins. They both have gills on their necks and then again on their abdomen, somewhat hidden by their arms. Unlike the previous specimen, this one seems to have a dorsal fin on his back, and a crimson colored tail. It’s unclear why this subject has one and the smaller one doesn’t. He’s approximately 246 pounds and seven foot two from the top of his head to his tail. His size leads me to the believe that he’s possibly older than subject M1945, dubbed as “Steve”. This one seems more aggressive, having needed to be sedated three times before he could be looked at.

More scientific research needs to be done to determine how they procreate and how they interact in the wild.


	3. Tag, You're It

**Summary for the Chapter:**

> Things get just a little worse for the merman duo.

Steve and Bucky were introduced to the public two days after they’d come into the aquatic park, and the pair were inseparable. The little Omega clung onto his Alpha any way that he could, keeping him close as if he was afraid Bucky was going to leave him again. As a result of them being constantly together, it was difficult for the trainers to actually train with them because every time they got close, Bucky would start growling, flashing his sharp teeth making them back off. The two had ‘mated’ several times, only making Steve start yelling out, not that he seemed to be in distress. Sam and Natasha just made sure they had food as they got used to being in their enclosure. It was Steve who detached from Bucky first, the Alpha only making distressed noises whenever Steve was so much as a few feet away from him. No matter what he did though, Bucky swam after him, but it wasn’t like they could really go anywhere. “Steve-” Bucky whined, trailing after his Omega as he stretched his muscles.

“Buck, I’m not goin’ anywhere. Really. I made friends with the humans here. I just wanna say hi,” he pouted, turning so he could look at him somewhat over his shoulder. Bucky only seemed to scowl, clearly not liking that idea as much as Steve did. “Buck, really, it’s fine. The brown man’s name is Sam and he’s really nice. He taught me how to talk to them. Why would he do that if he didn’t want to talk to me?” He asked, crossing his arms over his chest. Bucky swam closer, nuzzling into his mate’s stomach, clearly not all put off by Steve’s insistence to be momentarily separated.

“I’m just tryin’ to look out for you,” he complained, looking at him at Steve through his lashes. “I mean you were taken… I thought I was never gonna see you again. Stevie, I can’t picture my life without you in it. I don’t care if we’re stuck here together forever, just as long as we’re together. Just the two of us,” he hummed, swimming up a little higher so he could kiss his Omega’s nose. “Cuz you’re all I need, my special little starfish,” Bucky teased, only making Steve roll his eyes in exasperated fondness.

“I’m a starfish now?” He asked, lightly pushing Bucky away from his stomach.

“You’ve always been my special little starfish. You just don’t show it half the time,” Bucky stated, pressing his cheek back against Steve’s stomach, clearly not at all fazed by the little Omega’s attitude. “Because you’re too busy being a punk. But I’m pretty sure that’s just a phase,” he teased as Steve once again pushed him away. “Or should I say, hopefully it’s just a phase.”

Steve rolled his eyes, pushing Bucky away from himself as he swam closer to the humans that were looking through the glass window under the water. The little Omega swam by, giving them a little show as he made his way over to where Sam was watching them from the wet deck. “Sam! Sam! Steve fish!” He chirped, hauling himself onto the wet deck, making his poor Alpha whimpering next to him, clearly trying to get Steve back into the water. The Omega swatted his hand away, scowling at him before beaming back up to Sam expectantly. “Steve fish!” He repeated, clapping his hands as the human grabbed his bucket.

“You willing to do some tricks for me to get them?” Sam asked, watching the two creatures act together. From what they’d gathered, they were definitely a couple, their night activities greatly leading them to believe that they were both for sure males, not that there’d really ever been any doubt. They also seemed to have a lot in common with their human counterparts what with the way they interacted. The two hadn’t really fought since they’d been here though, apparently having gotten that out of their system on the first day, leading them all to believe that before this, they’d probably spent all of their time together anyway. Although, Bucky seemed far more protective of Steve the longer they stayed here. This was really the first time the little Omega had separated from his hold willingly.

“Steve tricks?” Steve asked, giving him a somewhat confused look before looking back to the bucket. Steve knew, logically, that he could just sing to get what he wanted, which currently happened to be the fish at Sam’s side, but he’d be good, just this once, he supposed. “To Steve fish?” Sam could only nod in response. Steve looked to his mate, giving him a smile before sliding back into the water before quickly bolting away. Given that Steve had a lithe frame, he was very fast and agile, able to make quick turns before whatever was following could compute. For obvious reasons, this led to a game of tag, Bucky chasing after his Omega. Sadly however, Bucky had lost an arm, and his whole center of gravity had shifted with it, making him crash into the glass. All it did was scare some of the humans that’d been watching them curiously, as Bucky quickly recovered, frowning at his Omega who busied himself with flips and spins in the air, clearly being a show off for anyone that just happened to be watching. Bucky waited until Steve was distracted with entertaining a child through the glass before he ran into him from behind, slamming the pair of them against the glass, making the child jump before bursting out in tears. Bucky didn’t seem to care though as he happily hung onto his Omega, nuzzling his neck as he tried regaining his bearings. It was easy to maneuver him onto his back so he could go back to Sam, giving him an unimpressed look.

“...Is he okay?” The human asked, clearly somewhat concerned about how suddenly Steve seemed to suddenly be green in the gills. Bucky looked over at his mate, nosing his cheek, only getting a whimper in response. The Omega was clearly not going to be doing anymore tricks. Sam frowned but threw them the fish, keeping a close eye on them as Natasha walked over.

“...He might be catching something. They’re not used to our eco-system here,” Natasha stated, watching the pair with a calculated expression on her face. “After all, we don’t really understand them all that well. Or maybe he just hit the glass too hard. “Hey Bucky, can you bring Steve closer so I can make sure he’s okay?” She called out over the water, only earning a glare in return as Bucky dove back down into the water, dragging Steve down with him. The Omega didn’t put up too much of a fight, letting Bucky pull him down as he made his sad little whimpery noises. The humans watched them, frowns firm on their faces. After a few moments of perfect silence, Bucky reappeared, hesitantly bringing Steve closer so they could look at him. “We’ll bring him right back to you,” Natasha stated, radioing Tony over so he could get the equipment they needed to move the heavy merman so he could examine him. “Everything will be okay," She assured before Bucky reluctantly backed away, sinking in the water until just his eyes were showing. Bucky watched as Tony came, taking his Omega away, his gaze intense on whatever he was focused on. 

* * *

 Tony took Steve back to his and Bruce's lab, setting up the equipment that they needed in order to run their tests. He took a few blood samples as he jumped into his work, going over every little thing as he went. When he the x-ray machine to see if Steve had broken anything, he blinked, clearly confused. "Hey Bruce, what does this look like to you?" Tony asked, as Bruce came over to look at whatever Tony had pointed out. 

"...Is that even possible?" the brunet asked, pushing up his glasses as he squinted. "Wheel the other machine over, I want a better look," he frowned, Tony quickly moving to get the machine. When they turned it on, pointing it in the same place as they'd seen the strange thing before, it all became apparent.

"...Well, I'll be damned." Tony said, at a loss for words. Steve was pregnant. Not with just one baby either. The merman was having twins.

**Notes for the Chapter:**

> Sorry for the long wait, the semester was insane, I got a job, and my laptop is still needing to be sent into the shop. I'll update when I can.


	4. The Cost of Admission is at an All Time High

**Summary for the Chapter:**

> Bucky gets irritated and some stuff goes down. If you don't wanna read about a merman killing a human don't read after the cut.

**Notes for the Chapter:**

> Sorry this took so long to get to you guys. My laptop's keyboard stopped working and needed to be sent in and I was left with my phone. On top of that, my work schedule has been crazy intense. I'll try to get the next chapter to you sooner.

Steve was brought back to his and Bucky’s tank as Tony mentally freaked out. First of all, both of these creatures were  _ males _ , it shouldn’t be possible to conceive at all, let alone twins. Second of all, with news like this, they might have to separate the pair, and he wasn’t sure that would go over well for them. They did seem kind of attached at the hip, besides… Would that even be good for the babies that they were having? Did they even  _ know _ Steve was pregnant? Tony didn’t want to have to tell the higher ups about this at all, but knew, responsibly, that if he didn’t, Bruce would. And Fury would tell Pierce… That would be a total shitshow, he already could feel the headache coming on. The poor goateed brunet helped Steve into the water, handing him over to Bucky who quickly darted the two of them back under the water. Tony could still see them given that there was no hiding in their tank, but he knew Bucky chose that spot because it offered the fewest eyes. “I’ll do everything I can to make this okay, guys. I promise,” he murmured softly to himself before walking away to go tell Banner to keep a lid on it. And to tell Fury to buzz off because he didn’t like the idea of the park owner finding out. It was all around known that Alexander Pierce was kind of a huge dick, taking out the competition one by one. He’d quit if it wasn’t for the fact that he was worried about the animals that would be left not in his care. 

“Ya know, if you keep sighing like that, someone is going to assume something is wrong,” Bruce stated when he got back into what Tony liked to call the center of scientific awesomeness. 

“Yeah well, it’s really hard to bottle up all this frustration I have for our pirate captain of a boss. Why am I not in charge? I have the looks that the ladies come swooning for, and charm for the ages,” he pointed out with a pout. He’d never understand why he’d get stuck here for the rest of his natural life. “At least we have fun here with the animals. Speaking of which, don’t tell anyone about the whole, pregnant merman thing. I want to try and keep this as tight lipped as possible. I can’t imagine press would be good for him. We barely know anything about their species after all.” Bruce’s only response was a somewhat hesitant nod. He knew, logically, that this was going to get out. There was just no way logically, that they could keep it hidden forever, seeing as how Steve didn’t seem to be carrying eggs. Meaning it was going to be a live birth, which would definitely mean he was going to get bigger.

Bucky, none the wiser of the predicament him and his blond Omega were in, simply continued to run his fingers through Steve’s hair, nosing his neck as he held him close. The Alpha was more than happy to hide from their human guests, scowling over at the glass as someone knocked on it. He hated them so much right now. Could they not tell that he was trying to make his mate more comfortable. He would have gone over to scare them if he wasn’t so worried about Steve so much. “Come on baby, open your pretty blue eyes for me… Just as deep and blue as the ocean. I know you can, baby…” he murmured softly, kissing Steve’s temple as the Omega let out this tired groan.

“Buck, m’tryin’ta sleep…” he complained, curling up closer to his Alpha as he simply made himself more comfortable. 

“I can see that, ya punk. Had me worried sick. Come on, why don’tcha grab onto my back. Not moving is making my fin ache,” he complained, carefully maneuvering Steve so he was groggily clinging onto Bucky’s back, the small Omega only protesting a little bit at being moved. “Ya look a little green around the gills, Stevie, ya sure you’re okay? Did the humans say anything about what it might be? You aren’t dyin’ on me, are ya?” he asked, trying not to sound as worried as he actually was. 

Steve didn’t reply right away, thinking about Bucky’s question. He didn’t remember leaving the tank, making him frown to himself. He hated not knowing things, especially when they concerned him. “No. I don’t remember. I don’t think I’m dyin’ tho. I feel like they woulda kept me in a new place to keep a closer eye on us. And seeing as how I’m here with you… M’probably just disagreein’ with the fish they gave us,” he hummed softly, nuzzling Bucky’s back as he made himself more comfortable.

“Then why are you the only one sick and not me too? I ate the same fish that you did…” the Alpha frowned, moving them forward, ignoring the curious humans at the glass that were flashing bright lights at them. 

“I dunno. Maybe it was just one bad fish. Shuddup and lemme sleep, Buck. M’tired,” he whined, his tail slapping against Bucky’s in an attempt to get him to stop worrying so damn much. Really, he was thinking way too loud for Steve’s comfort. Maybe it was just the fact that they hadn’t been here very long and Steve was already sick…?

“Wait Steve- What if- What if the reason you aren’t feelin’ good is cuz-” Bucky started before he realized that Steve had fallen asleep on his back. Which wasn’t really all that surprising considering the day that they had. “What if you’re carryin’ a pup…?” he murmured to himself, mouth set in a thin line. He needed time to think about this. Preferably with less humans snooping about. But there were ways to handle that... Ones he knew Steve might not approve of, but he didn't care. If he thought the fish was making him sick, well then Bucky would give him something completely new to chew on. Consequences be damned.

* * *

Steve was woken up by the sound of screaming. It was then that he realized that he wasn't on Bucky's back anymore, his mate having apparently put him down in a secluded part of their tank away from prying eyes. He swam up, looking for his mate. That's when he spotted the humans, some of them screaming, others running around. "Stevie! I got you food~!" Bucky chirped happily as he swam closer. That's when he noted how the water was in fact, tinted red. 

"Bucky, did you kill somebody?" he asked, his eyes the size of the moon as Bucky offered him what looked to be an arm. 

"Yeah, I did. You said the fish was making you sick, and they kept trying to wake you up. So I jumped up and drowned him. That'll teach them to leave us alone," Bucky grinned, his teeth bloody. There was a moment of silence as Steve seemed to process this information before he nodded to himself, a small smile on his face. 

"Thank you Buck, that was very sweet of you."

"Course, Stevie. Anything for the mother of any future pups~" the Alpha teased, giving his Omega a chaste kiss on the lips.

 


	5. Two For the Price of One

**Summary for the Chapter:**

> It's just one of those days at the park. Twins pups, drama within the park, crying...

Steve clearly didn’t mind that Bucky had killed a human in order to make him happy, being much more affectionate now that he wasn’t feeling so crappy. But while all was well for the two merman, it wasn’t as smooth sailing everywhere else. The security guards did the best they could to get the panicked people away from the exhibit, the entire park now going on high alert. This kind of thing wasn’t exactly common at the park. The last death had been literal years ago, not long after they’d opened the gates to the public. Of course there had been a few close calls, but it’d never been a guest to have been the one in danger, it had always been a trainer. Meaning it sure as hell hadn’t been a child. Sam groaned as he realized the amount of backlash this was going to create. At least the public would realizing how dangerous they were now… They put Coulson in charge of getting the half eaten boy out of the water and away from the two carnivores.

“What do you think upset them?” Sam asked, looking over at Natasha as he watched them nibble on the flesh of their victims. Honestly, he knew they were dangerous, but he didn’t think they’d actually go and kill someone. Maim them maybe.

“Well, Tony sent out an urgent text message saying that Steve is pregnant. So I’m guessing they lashed out because of something along the lines of hormones,” Natasha shrugged as she showed the text to Sam before pocketing the device for safe keeping. 

“He’s pregnant? How is that possible-? He’s a guy-?” Sam floundered for a possible scientific explanation. Sadly, science wasn’t his strong suit. That’s why he trained the animals. 

“I don’t know Sam, why don’t you ask him. Steve seems to like you the best,” she noted as she gave him a pointed look. She turned away so she was facing the merman tank, watching as Coulson cautiously pulled the carcass out of the water while the two mermen were distracted. Steve seemed to be feeling better at least, which she counted as a blessing. “Just ask him, because I doubt he’ll put up with Tony. Especially since he seems to be freaking out because apparently Pepper is taking the merman story.”

“Pepper? Pepper Potts? Didn’t she and Tony break up on bad terms?” Sam asked, biting his lip as Natasha nodded. 

“I don’t know all the details. I just know that Tony is still kind of bitter about it. He refuses to talk about her. Not that I blame him,” she shrugged as she walked closer to the water. She watched Steve nuzzle up to his mate, a dorky smile on his face as he licked his sharp teeth. 

“I totally understand to be honest. From what I remember she was a piece of work that Pepper. At least he has Bruce now. Right? I didn’t misread that, did I? They’re together?” he asked. Natasha granted him a nod for his troubles before helping Coulson out of the water. The poor man was calm on the exterior but it was clear to those who knew him that he was somewhat frazzled. 

“Please tell me we’re not going to make this a regular occurrence,” he said, looking back at the two mermen who seemed to have no problem ignoring all the humans around them as they happily clicked back and forth to each other. “What I wouldn’t give to understand them,” he muttered wistfully to himself before nodding. “Alright, I have to go talk with Fury. Hopefully the higher ups won’t want to come and investigate. We’re going to try and keep this as under wraps as possible,” he stated before offering them a salute. The two trainers exchanged a look with each other before nodding. The last thing they wanted was Pierce coming down. He’d probably try and sell them off to the highest bidder. 

“Hopefully this was a one time thing though,” Sam sighed as he walked closer to the edge of the water, squatting down as he called Steve over. The little blond merman clicked at Bucky softly before he kissed his cheek. 

“Buck, I gotta go see what he wants-” he huffed when Bucky grabbed hold of Steve’s arm. “Just come with if you’re so keen on protecting me, Buck, geez,” he hummed, giving him another kiss as he dragged his mate over. “Sam!” the merman chirped in English, looking up at his trainer with this ridiculously happy smile. Almost like he wasn’t at all phased of the mess that they’d found themselves in. 

“...It’s wrong to eat people, guys,” Sam started, watching as Steve turned to relay the message to Bucky in clicks. The brunet snorted loudly, shrugging as he nuzzled Steve’s neck, clicking something back.

“Bucky only want mate happy,” Steve responded, apparently not really seeing anything wrong with what they’d done. His ancestors had killed people  _ all _ the time, and that’d been just for fun. At least they’d eaten the human. They weren’t being so wasteful. Maybe they’d be happier if they’d just left the human floating in the water? “Wanted better fish,” he explained, putting his hands against his stomach. “Not feel well.”

“...Okay… That’s still not a good excuse to eat people, guys. If you wanted different fish, all you needed to do was tell us,” he scolded as Natasha squatted down next to him. 

“Exactly. It doesn’t matter if you’re expecting young or not,” she agreed. Steve quickly looked to Bucky when she said that, giving him a look.

“...Expecting?” the little Omega asked his mate, squinting at him.

“I think they mean you’re pregnant,” Bucky hummed, putting his palm against Steve’s currently flat stomach.

“But I- Oh. Bucky… Buck I can’t-” he deflated, before he literally burst into a sobbing fit, clinging to his Alpha as he had his emotional breakdown. He was so scared… Pups? This far away from home? They’d talked about having pups, maybe one day, but definitely not right now. Steve wanted to get back to the ocean before they had any, but now… Bucky held Steve to him the best he could with one arm, petting his Omega’s back as he sobbed. He was so preoccupied with Steve that he hadn’t noticed when the humans exchanged a look with each other. 

“I guess now would be a bad time to tell them they’re having two, huh?” Tony asked with a frown, watching the scene in front of him unfold. The Omega in Bucky’s arm only got louder. “...Should we sedate him do you think? I don’t want them accidently, or intentionally killing someone else,” he frowned.

“Steve, baby, please- Stop crying, I’ve got you… We’re gonna be okay… We’ll figure this out,” Bucky murmured softly, literally littering Steve’s face with kisses. The Omega slowly quieted down, sniffling as he wiped his nose on his hand. 

“...You sure…?” he asked feebly, looking up at him with tear filled eyes. Bucky nodded, kissing Steve’s nose.

“Of course. You me, and the pup,” he hummed softly.

“...Buck they said twins…” he whimpered, burying his face in Bucky’s neck. 

“Okay, you, me, and the pups- Wait- Steve- Your ma said-”

“I know what she said Buck,” he whimpered, sniffling pitifully. Sarah had told Steve several times when he’d planned on mating with Bucky, that it was dangerous for him to have pups. She cautioned him that since male Omega’s were more fragile, it was highly unlikely that he’d make it out of a pregnancy completely intact. Chances are, it’d probably end up being either him or the pup. Of course there was always the chance he’d give birth early but… it was still unlikely they’d both be okay. Granted now they had the humans...Maybe they’d help... 

**Notes for the Chapter:**

> Thank you /so/ much to everyone who's stuck with me so far. I promise I have big plans for this story. Sorry if I had any of you worried about who's arm it was. You guys would know if I killed off someone important(:

**Author's Note:**

> Reviews, comments, and kudos are the life blood I need to keep writing. 
> 
> Join me on Tumblr! www.captainthirsty1945.tumblr.com

**Works inspired by this one:**

  * [Creatures of the Sea; New Bulliten](https://archiveofourown.org/works/7716865) by [TheOneFromTheForest](https://archiveofourown.org/users/TheOneFromTheForest/pseuds/TheOneFromTheForest)
  * [Sirens' song](https://archiveofourown.org/works/10598808) by [Guestpass](https://archiveofourown.org/users/Guestpass/pseuds/Guestpass)




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